idle speed preferences?

sald

Member
I was just at a tractor pull with a bunch of Farmalls. One was a model A like mine. The guy had the idle at 800 rpm. Said it was "better"
What do you all have preferences for, and why?
I know they have 525 in the manual.
 
I don't know. I couldn't get to ask him why. I just wanted to see if there were advantages to it that I was unaware of.
 
A low idle speed is best for shutting off the engine so the engine doesn't spin over due to inertia so long and suck in lots of unburned gasoline and air mixture and wash the oil off the cylinder walls. Besides that, I typically idle my SH & M about 700-800 rpm, idling at really low engine speed really reduces the amount of oil circulating around the engine, really slows up coolant flow, no up side to low idle speed except when shutting engine off.
 
As slow as it will Idle keeps it from running on (from self -hot spot- ignition) idling for long periods will not hurt it, but
might not charge the battery enough to keep up with use. If worked like it was designed to, 800 rpm will most certainly keep
running when shut off. Jim
 
If your getting "dieseling" when you shut a hot tractor engine off you are not letting it idle and cool off near long enough after running it hard. Dieseling is when glowing hot carbon in the combustion chamber ignites the incoming fuel/air mixture instead of the spark plug. Only thing harder on the engine is when the engine diesel's Backwards.

Our Super M-TA was prone to dieseling, running on if plowing or disking, pulling it hard, even idling at 450 rpm didn't prevent the run-on. Had it happen a couple times, even after running a quarter mile in 4th gear to the intersection of our road and county road, and running the quarter mile to our farm in 5th gear. If you didn't let it idle another 4-5 minutes about half the time it would run on, had to shut it off in gear with clutch in, and let clutch out as engine slowed. Had to be careful, if it dieseled backwards the TA would let it spin in the low side.
 
I prefer a lower idle speed too.

It could be that the idle circuit in the carburetor was partly plugged, so the tractor could not run without the governor hunting at a lower idle speed.
 
Had a guy tell me he likes them idled up a bit. His theory on an older and worn engine, may not have enough oil pressure to reach all points requiring lubrication due to low oil pressure at a low idle. Interesting view.
 

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